The general goal of this research proposal is two-fold: first, to employ the single barnacle muscle fiber as a preparation, together with tow cell-free model systems, viz, the photoprotein aequorin and firefly (luciferase-luciferin) to test the general working hypothesis that certain chlorophenols, e.g. pentachlorophenol, act as cellular toxins by raising the internal free Ca2+ level and by reducing the internal ATP and phosphagen levels. Thus, the hypothesis assumes that cell death is primarily the outcome of Ca2+-"overload" and ATP depletion. And second to explore three possibilities: (1) that the internal free Ca2+ concentration can be stabilized by microinjecting EGTA or BAPTA (Ca2+ chelators) beforehand, a situation which may lead to the arrestation or reversal of most of the pathophysiological effects of Ca2+ overload. (2) That the internal ATPMg (and ArP) levels can manipulated by preinjecting ATPMg. Arp or both substances. And (3) that an optimal therapeutic ATPMg (or ArP and ATPMg). Such an approach to the problem of cytotoxicity is of interest, particularly since it involves (1) the use of a in situ model system and 2 cell-free systems: (2) a single muscle fiber preparation that is known to be ideal for microinjection studies; (3) a preparation whose general membrane transport mechanisms preparation which is known to be very sensitive to a number of toxic substances, notably thymol, Hg, Al and pentachlorophenol. As for the technical aspects of the proposed work, multidisciplinary techniques, involving radioisotopes, photoproteins, microelectrodes, assays, gel electrophoresis and so on, are available in this laboratory. The facilities necessary for the conduct of this type of work are also available. This line of investigation represents a new approach, particularly since virtually nothing is known about the cytoxicity of chlorinated phenols e.g. pentachlorophenol, as it relates to membrane transport mechanisms. Simply put, the bio-hazards of pentachlorophenol are of prime public concern both at the national and international level.